Hello there,
I am currently trying to put together a 4x4x4 RGB LED Cube, in hopes that I can use what I learn to make a larger one in the near future, but I am having issues figuring out how to switch the source current for each multiplexed layer.
I would really like to use the TLC5940 LED Driver, and for this I will need to sink the current into the driver. To multiplex I am planning on using a transitor, of course, to source the current for each individual layer. After a fair amount of research I have decided that using a P-Channel Enhancement Type MOSFET is the component I would like to use. For these components I understand that 0v on the gate will restrict current flow and a negative gate voltage past the threshold will allow current to flow through the source and drain. I would like to switch the MOSFET directly from an Arduino pin, but I don't know how to apply a negative Voltage on the gate to switch it on. My understanding is that PNP BJTs operate on sort of the same principle, where the base needs a negative current, instead of voltage, to allow current flow between the emitter and collector. In my mind the Arduino pins only operate between 0v to 5v and I can't wrap my mind around how to pull the gate negative. Maybe I'm not understanding the basic principle behind how these transistors operate, but if anyone can please point me in the right direction it would be greatly appreciated!
Also, I don't have a specific MOSFET in mind yet, I kind of wanted to make sure I have the theory down first, but I was wondering how you prefer to go about finding the right components to fit your projects.